Depressed Mood Improvement Through Nicotine Dosing (Depressed MIND Study)

Late-life depression (LLD) is characterized both by affective symptoms and cognitive deficits. The co-occurrence of cognitive deficits in LLD is a clinically relevant phenotype characterized by significant disability and poor antidepressant response. Cognitive deficits can persist even with successful antidepressant treatment and increase the risk of depression relapse. Despite the clinical importance of cognitive deficits in LLD, there are no established treatments that specifically target cognition in this population. The lack of treatments that improve cognitive deficits in depression is a deficiency in current therapeutics. Modulation of the cholinergic system by nicotinic receptor stimulation may improve both mood and cognition in depressed elders. Clinically, transdermal nicotine improves mood in smokers and a placebo-controlled pilot trial in nonsmoking adults found that transdermal nicotine significantly improved mood. In a previous trial examining Mild Cognitive Impairment, transdermal nicotine safely improved cognitive function on tests of attention, episodic memory, and processing speed. These same cognitive domains are impaired in LLD. The investigators hypothesize that these effects on mood and cognition are mediated through nicotine's effect to increase cognitive control network activity and reduce default mode network (DMN) activity. This pattern of network activity during tasks demanding external attention is associated with better task performance. Furthermore, as seen in smokers, nicotine's effect on these networks reduces depression's bias to negatively valenced stimuli and decreases rumination. The central hypothesis is that in LLD, transdermal nicotine will safely improve depression by increasing activity in cognitive control regions and decreasing activity in DMN regions. This will result in a decreased attentional bias to and reactivity to negative stimuli. A secondary hypothesis is that transdermal nicotine will also improve subjective and objective cognitive performance through these same network effects. Primary Aim 1: To determine whether administration of transdermal nicotine over 12 weeks improves clinical symptoms in patients with LLD with subjective cognitive impairment (SCI). Hypothesis 1: Transdermal nicotine administration will result in reductions in depression severity measured by the Montgomery-Asberg Depression Rating Scale (MADRS; primary mood outcome). It will also result in improvement in broader assessments of depressive symptomatology, including anhedonia, apathy, fatigue, sleep, and rumination (secondary outcomes). Hypothesis 2: Transdermal nicotine administration will result in improvements in attentional performance on the Conner's Continuous Performance Task (CPT; primary cognitive outcome). It will also result in improvement in subjective and objective cognitive performance on other tasks measuring attention, episodic memory, working memory, processing speed, and executive function (secondary outcomes). Secondary Aim 2: To determine whether administration of transdermal nicotine over 12 weeks modulates canonical intrinsic functional network activity in LLD with SCI. Hypothesis 3: On repeat administration of the Posner task of external attention, transdermal nicotine administration will result in increased activity within the cognitive control network and decreased activity within the default mode network. Hypothesis 4: Transdermal nicotine administration will result in increased functional connectivity within the cognitive control network and decreased connectivity within the default mode network at rest. Hypothesis 5: Changes in intrinsic network activity / connectivity with transdermal nicotine administration will be associated with changes in mood symptoms and subjective and objective cognitive performance.